Is personality heritable?

The left, which contains some of the people most angrily pro-evolution, don't think so.  Somehow, evolution which applies to every aspect of living things, has stopped cold before laying a finger on the mental attributes of humans.  Personality, intelligence, ability, mental traits, all are to be attributed to the influence of anything except genes.

 

The Derb comments at The Corner on NRO:

Jim:  Your main point (and Dana Goldstein's) about genome-wide association studies is well taken.

Goldstein's closing observation, though, makes no sense.

Just as selection turns out to have pruned away most disease-causing variants, it has also maximized human cognitive capacities because these are so critical to survival. "My best guess is that human intelligence was always a helpful thing in most places and times and we have all been under strong selection to be as bright as we can be," [Goldstein] said.

There are so many things wrong with that, it's hard to know where to start. Perhaps with Razib's observation that intelligence does not contribute to fitness in all times and places, and may work against it, as in modern welfare states. (Razib has a neat graph illustrating this. Someone made a movie about it, too.) 

[And a note to readers who think that "fitness" is something to do with Conan-esque Blond Beasts lopping the heads off weaker specimens with their broad-axes. Nope: it's just a genetics term of art for the probability of a genome passing its material into the next generation. As I have pointed out before here, if you were to list organisms in terms of their genomes' proven fitness, the humble sea cucumber (400 million years and counting) would be way up near the top, saber-tooth tigers (extinct after a million years or so) far down towards the bottom.]

And then, natural selection operates with different degrees of force in different places. Environment A might have put its human inhabitants under intense selection for intelligence, environment B, less so for its.

This is Biology 101, and it's inconceivable Goldstein doesn't know it. So why did he say such a daft thing? Perhaps someone should ask him.

And while you are right about the difficulty of tracing pathways from genotype to phenotype for quantitative traits like intelligence and personality, we have the word of James Watson, who surely knows a thing or two about genetics, that the difficulties will soon yield to investigation. From the very end of Watson's book:

So I was not surprised when Derek [Bok, then-President of Harvard], who had spent most of our meeting listening, asked apprehensively how many years would pass before the key genes affecting differences in human intelligence would be found. My back-of-the-envelope answer of "15 years" meant that [Larry] Summers' then undetermined successor would not necessarily need to handle this very hot potato.

Upon returning to the Yard, however, I wondered if even 10 years would pass.

That the pathways exist, we can be certain. Evidence from the "other end" — sociology, psychometry, twin studies — is overwhelming. The things we learn, mainly in our childhood, are laid down on a genetically-determined substratum. Doesn't every parent know this? (Not just parents, either. When I posted on this once before, a couple of years ago, I got an email from a dog breeder to the effect that: "Duh. If personality were not heritable, I'd be out of business.")